Technical Field
The present disclosure relates to a liquid level detector.
Background Art
There are known liquid level detectors. For example, JP-B-4681127 discloses a liquid level detector as described below. This liquid level detector is configured to detect a bath level of a molten metal. Specifically, the liquid level detector has an open vessel, an upper part of which is open. The open vessel has a sidewall in which a plurality of thermocouples are embedded to measure a heat flux difference. From the measurement results, a bath level is calculated. The heat flux difference is a difference between a heat flux flowing from a molten metal (liquid) inside the vessel toward outside the vessel, and a heat flux flowing from a gas above the bath level toward outside the vessel. Being an open vessel, there is a temperature difference between the molten metal and the gas, causing a heat flux difference based on which a bath level can be calculated.
PTL 1 JP-B-4681127
In the case of a hermetically closed vessel, however, there is almost no temperature difference between a liquid and a gas inside the vessel, causing no heat flux difference, and hence the liquid level cannot be detected by the conventional art described above.
Moreover, as is apparent from the fact that the thermocouples are embedded in the sidewall of the vessel, with the technique disclosed in the patent literature mentioned above, the liquid level of a liquid inside the vessel is detected, but the liquid level of the liquid not contained in the vessel is not detected.